Regulator for electric-lighting systems on motor-vehicles



J. W. FITZGERALD.

ETECULATCR ECR ELECTRIC LTCHTTNC sYsTEMs oN MoToR VEHICLES.

APPLICATION FILED MAIL23, 1918. 1,373,806. Patented Apr. 5, 1921.

Sme/Moz @Wj/WM amano?! JOHN W. FITZ GERALD, OF DETROIT, MICHIGAN.

REGULATOR '.FOR ELECTRIC-LIGHTING SYSTEMS ON MOTOR-VEHICLES Specification of Letters Patent.

Application led March 23, 1918. Serial No. 224,151.

To all whom it may concern Be it known that I, JOHN W. FITZ GERALD, a citizen of the United States of America, residing at Detroit, in the county of 'lVayne and State of Michigan, .have invented cer-.

tain new and useful Improvements in Regulators for Electric-Lighting Systems on Motor-Vehicles, of which the following is a specification, reference being had therein to the accompanying drawings.

The invention relates to regulators for electric currents, -being more particularly designed for use in connection with lighting systems for motor vehicles, such for instance as systems adapted for installation on the Ford type of car. In this type the current for the lights is obtained directly from the magneto generator without the use of a storage battery, and it is usual to place the lamps for the two headlights in series with each other. The resistance of the two lamps thus placed is such as to obtain the desired illumination when running at normal speed, but an increase in speed will produce an objectionable intensity of' light, while at low speed the illumination is insuiiicient. i

To overcome these .ditliculties I have devised a system in which, instead of placing the two lights in series, they are arranged in multiple or in independent circuits. This will lower the resistance suliiciently so that in starting and when the motor is running at low speed there will still be suflicient current passing through the lamp circuit to produce proper illumination.V To control thecurrent at higher speeds I place in the circuit a resistance device, by means of which resistance is added as thevoltage increases so as to maintain nearly a constant current through each lamp.

. also made for preventing the cutting in of this resistance unt-il a predetermined current is flowing through the lamp circuit, and for then cuttingin the resistance in progressively lessening increments corresponding to the curve of the voltage rise. Thus with my improved system the illumination is substantially constant without regard to the speed.

In the drawings:

Figure l is a diagram showing my improved system;

Fig. 2 is a similar view illustrating a modification.

A is the magneto generator and B and B are the lamps for the two'headlights which rovision is,

are'included in separate circuits C and C. In each of these circuits is arranged in series with the lamp a regulator D, preferably. of the following construction.

E is a casing, within which is arranged a variable resistor F, the resistance of which Patented Apr. 5, 1921.

is lowered by compression and is raised -by f' expansion. As shown in F ig. l, the resistoris formed of a series of annulardisks of carbonized cloth or other suitable material having a relatively high resistance and possessing a degree of resiliency which permits eX- pansion on release of pressure. Through the space within these disks extends a conductor G which has a relatively high coei'iicient o f expansion and is so proportioned in resistance as to rise in temperature rapidly within a relatively small variation of current volume. Preferably I employ silver wire on account of its high coeiiicient of expansion and high electrical conductivit One end of the wire G is attached to a movable follower H at one end of the casing E and bearing against the resistor. The other end of the conductor G passes out from the casing and is attached to a spring I. rlhe follower H is also attached to a spring d tensioned to exert a pull in the opposite direction from that of the spring I, but to a 4lesser degree. The conductor G and resistor F are included in the lamp circuit, 'the current being conveyed to the conductor G through a contact member K slidably bearing thereon,and from this conductor to the follower H and resistor F, thebpposite end of which is connected to the conductor of the lamp circuit. L is a stop member secured to the conductor G and adapted on a predetermined expansion of the latter to contact with the member K, which then coperates to arrest further movement.

lVith the construction as thus far de- .scribed in operation, the tension of 'the spring I acting through the wire G upon the follower H will compress the resistor F so as to lower the resistance thereof to the minimum. This will so lower the resistance of the lamp circuit that when the generator is running at low speed and is at relatively low voltage, there will still be current enough passing through the circuit to produce good illumination. i As' soon as there is any current iiowing through the circuit the heat generated in the wire G will cause the expansion of the same. but the expansion of the spring Iis sufficient to maintain the wire G taut and to exert substantially the Q i Y1,373,606

same pull thereon. This continues until thev4 expansion is suflicient to bring the stop L into contact with the coperating stop K,

Ywhich arrests further movement in thisdirection. With continued increase in the current volume the wire G is further expandedv and as the spring I can no longer take up this expansion the spring J comes into action and draws the wire and the follower H -in the opposite direction. This, by'releasing l pressure upon the resistor F, will increase the resistance thereof, and as the current is compelled to traverse this resistor in passing v through the lamp circuit the flow of c urrent will be controlled. The same action will continue throughout the entire range of variation of speed and voltageof thel generator, and although there is a constant risein current volume passing through the lamp circuit lthe increase is nevertheless so restricted as to not produce an objectionable variation in the intensity of the light.

The voltage curve ofthe generator is such that the rise of voltage is most rapid at low speeds and diminishes' at higher speeds, due l to inductive reactance. To counteracta corresponding rise in current it is necessary to cut inV resistance more ra idly at vlow speeds that at higher speeds. revision for this effect is made in the construction illustrated in Fig'. 2, vin which the resistor is in the form of al conical spiral coil M, the convolutions of which are in contact when under the normal pressureof the spring I, but are separated progressively under the action of the spring J, the construction being otherwise thesame' as in Fig. 1. Thus in operation, after the wire G has been sufiiciently expanded to bring the contacts L and together, the further expansion will permit the" spring J to draw upon the conical coil M.

This will first separate the larger convolu tions from each other, and as the action progresses the smaller ones, with the effect that the resistance is 'increased by progressively decreasing increments.

What I claim as my invention is:

l. In an electric lighting system for motor vehicles, the combination with a generatorv varying in voltage with speed changes, of a lamp circuit and a regulator insaid lamp circuit comprising a variable resistance resistor, a yieldable tension device for increasing the resistance of said lresistor and opposed yieldable tension device greater than and normally overcoming the first-,mentioned tension device, a conductor forming a mechanical link between said last-mentioned tension device and the resistor and included in the circuit, said conductor being expansible in proportion to the current passing therethrough, and a stop foi limiting' the movement of said conductor when expanding in the direction in which it is actua-ted by said first-mentioned tension device,

whereby' the engagement with 'said stop will permit the lesser tension device toincrease the resistance in the circuit upon further expansion of said conductor.

2. In an electric lighting system for motor vehicles, the combination with agenerator varying in voltage with speed, of a lamp circuitl and a current regulator in said lamp circuit comprising an extensible resistor increasing in resistance as it is extended, a tension device for extending said resistor, an

opposed tension device greater than and overcoming said-iirst-mentioned tension device to hold said resistor contracted, a conductor forming a mechanical tie between said last-mentioned tension device and the resistor, being included in the electric circuit and being expansible in proportion to the current passing therethrough, and a stop for limiting movement of said conductor in the direction in lwhich it is actuated by the greater tension device, said stop being spaced to permit an initial expansion of said conductor upon increasein current in the circuit until'a predetermined lighting effect is obtained and then limiting movement in this direction to permit the opposed tension device to extend said resistor and increase resistance inthe circuit.

3. An electric current iregulator comprising a resistor, a yieldable tension device for increasing the resistance of said resistor, an opposed yieldable tension device greater than and normally overcoming the firstmentioned tension device, a conductor forming amechanical link between the last-mentioned tension device and the resistor included in an electric circuit, said conductor being expansible in proportion to the current passing therethrough, and a stop for limiting the movement of said conductor when expanding in the direction in which it is actuated by whereby the engagement with said stop will vpermit thelast-'mentioned tension device to increase the resistance in the circuit upon further expansion of said conductor.

4. In an electric system for motor vehicles, the combination with a generator varying in voltage with speed changes, of a lamp circuit and a current regulator for said lamp circuit comprising a compressible resistor and an. expansible conductor connected in series in said circuit, said resistor varying in resistance under different degrees of compression, and means acting through said conductor to subject said resistor to a compressive stress to decrease the resistance thereof, said stress being relieved through expansion of said conductor upon a predetermined flow of current therethrough to permit of expansion of said resistor and a consequent increase of the resistance of the saine.

In testimony whereof I aiix my signature.

JOHN w. rrrz GERALD,

said first-mentioned tension device, 

